accretion disk

noun

variants or less commonly accretion disc

plural accretion disks also accretion discs

: a disk of usually gaseous matter surrounding a massive celestial object (such as a black hole) in which the matter gradually spirals in toward and accretes onto the object as a result of gravitational attraction

Evans' team studied a supermassive black hole with jets 800 million light-years away named 3C 33. They never found an expected X-ray pattern … which results from light reflecting off the accretion disk.

—Bill Andrews

Most other moons are either captured planetesimals, or they formed along with the planet in a common accretion disc.

—Daniel Herwartz, et al.

Example Sentences

Recent Examples on the Web

The emitted X-rays can sometimes reflect off the accretion disk, creating ‘echoes’ of the initial emission. —Jennifer Ouellette, Ars Technica, 2 May 2022

These are called relativistic jets, and they're made of superheated plasma ejected from the accretion disk. —Nathaniel Scharping, Discover Magazine, 5 Apr. 2019

Rather, its energy comes from the radiation released by shockwaves on the surface of the protostar and its accretion disk. —Jennifer Ouellette, Ars Technica, 16 Nov. 2022

Most material in the accretion disk eventually ends up in the black hole. —Alison Klesman, Discover Magazine, 7 Apr. 2020

Material that falls toward a black hole first forms a flattened accretion disk orbiting around it. —Phil Plait, Scientific American, 20 Dec. 2022

Some of that light hits the accretion disk, which absorbs it, heats up, and then emits light of its own. —Alison Klesman, Discover Magazine, 5 Feb. 2019

Next up, there's the cloud of dust and gas itself, called an accretion disk. —Nathaniel Scharping, Discover Magazine, 5 Apr. 2019

The material is then collected into an accretion disk that feeds a central protostar, according to NASA. —Misty Severi, Washington Examiner, 12 Jan. 2023

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Word History

First Known Use

1972, in the meaning defined above